饱和粉细砂层隧道涌水流砂综合防治技术研究

Research on Comprehensive Prevention and Control Technology of Water Burst and Quicksand in Saturated Fine Sand Layer Tunn

饱和粉细砂由于施工扰动而呈流塑状,隧道穿越时易发生涌水流砂,施工安全风险极高。结合昆河铁路宝峰隧道工程,针对其下穿高速公路段位于富水饱和粉细砂地层,是典型的“烂洞子”,多次涌水流砂、溜坍,为确保公路正常运行和隧道施工安全,研发了智能深孔定向注浆及监测系统(获专利),采取“内层插入ϕ108大管棚注浆的拱部双排+隧底竖向网格+掌子面梅花+拱脚水平+锁脚斜向”布置的高压旋喷桩防治技术,同时旋喷后辅助磷酸水玻璃注浆堵砂堵水,形成隔水承载拱体系,确保了掌子面的稳定,成功解决了涌水流砂和溜坍等难题,实践表明:(1)“高压旋喷桩+大管棚+磷酸水玻璃注浆”综合防治技术方案在粉细砂层段应用,是成功的;(2)采用智能深孔定向注浆及监测系统,使超前加固达到了预期效果;(3)该综合防治技术的关键在于定向旋喷、旋撤速度及注浆压力的控制。

Because of the construction disturbance,the saturated fine sand is in a fluid⁃plastic state,and the water burst and quicksand are prone to occur when the tunnel is passed through,resulting in very high construction safety risks.Combined with the Baofeng tunnel project of Kunming⁃Hekou Railway,the section of the underpass expressway is located in the water⁃rich and saturated fine silt layer,which is a typical“rotten tunnel”with multiple gushes of water,sand and collapse.In order to ensure the normal operation of the highway and the safety of tunnel construction,the intelligent deep hole directional grouting and monitoring system is developed(patented).The comprehensive prevention and control technology of high pressure rotary jet pile with“double row of arch inserted intoϕ108 large pipe roof grouting+vertical grid at tunnel bottom+plinx on tunnel face+horizontal arch foot+diagonal lock foot”arrangement is adopted.At the same time,auxiliary water glass phosphate grouting is used to block sand and water after rotary spraying to form a water⁃bearing arch system,which ensures the stability of the tunnel surface and successfully solves the problems such as gushes of water,sand and collapse.Practice shows that:(1)the comprehensive control technical scheme of“high pressure rotary jet pile+large pipe roof+water glass phosphate grouting”has been successfully applied in the silty sand section;(2)the use of intelligent deep hole directional grouting and monitoring system enables the advance reinforcement to achieve the expected effects;(3)the key of the integrated control technology lies in the control of directional rotary jet,rotary withdrawal speed and grouting pressure.